1. Field of the Invention
The present invention relates to method of forming semiconductor chips, to the semiconductor chips so formed, and to a chip-stack package having the semiconductor chips.
2. Description of the Related Art
As electrical appliances are continually reduced in both size and weight, various methods of packaging semiconductor chips have been studied to replace the conventional method of wire-bonding in an attempt to help reduce the size and weight of the semiconductor packages used in the electrical appliances. Some of these packaging methods involve flip-chip bonding, wafer-level packaging, wafer-level stack packaging, and chip-stack packaging.
In the case of the chip-stack packaging, stacked semiconductor chips are electrically connected by through vias formed in the semiconductor chips. This may result in shorter length interconnects, which may provide high performance, high speed, low power consumption, and microminiaturization as compared to some of the other conventional packaging methods.
However, a semiconductor chip built in a chip-stack package typically involves a complicated fabrication process. This fabrication process typically includes the following steps. A connection hole is formed at edges of the semiconductor chip and filled with a metal layer, and then the metal layer is polished. However, before the connection hole is filled with the metal layer, an insulation layer, a barrier metal layer, and a seed layer are generally sequentially and conformally formed in the connection hole. The insulation layer helps prevent a leakage current. The barrier metal layer helps prevent the metal layer from being diffused. The seed layer aides in conformally and easily forming the metal layer. These processes for forming the semiconductor chip built in the chip-stack package, however, are very complicated. Furthermore, the thickness of the insulation layer formed in the connection hole is restricted by a width of the connection hole. Therefore, it is not easy to form the insulation layer having sufficient thickness to prevent the leakage current.